1. Field of the Invention
The present invention relates generally to the field of optical fiber connectors; and, more particularly, to an optical fiber connector termination having improved strain relief features.
2. Description of the Prior Art
It is desirable that the transfer of light between the optical fibers of mated optical fiber connectors be accomplished with a minimum loss of signal; i.e., with low insertion loss. Insertion loss may result from several factors, including the presence of a gap or separation between the ends of the connected fibers. Specifically, some light is lost if the end faces of two fibers are separated because light diverges as it radiates from the end of a fiber. In addition, fiber to fiber separation results in an insertion loss due to Fresnel reflections at the two glass-air interfaces between the spaced fibers. Accordingly, it is important that end faces of connected fibers be maintained in alignment and in virtual contact with one another to minimize these losses.
In many applications, however, optical fiber connectors can be subjected to severe external stresses which can damage the connectors and cause misalignment or separation of optical fibers mated by the connectors. For example, in applications where connectors are subject to frequent connection and disconnection, stresses placed on an optical fiber cable can loosen or otherwise damage the attachment of the cable to the connector and interfere with the efficient transmission of a signal between the optical fibers of mated connectors.
To protect the optical fibers, and to help maintain the integrity of optical fiber connections, it has become the practice to incorporate strain relief structure into optical fiber connectors to help isolate the delicate optical fibers from external stresses. Examples of strain relief structures for optical fiber connectors are disclosed in U.S. Pat. Nos. 4,588,256; 4,729,619 and 4,909,583.
Optical fiber cables typically include one or more centrally positioned buffer covered optical fibers surrounded by a load bearing member in the form of a plurality of elongated strength members which, in turn, is surrounded and enclosed by a flexible outer jacket. An optical fiber connector is attached to such a cable by attaching a cable termination portion of the connector to an end of the cable.
More particularly, a part of the cable jacket is first cut away to expose a length of the elongated strength members and the optical fibers therein. The exposed end of the cable is inserted into a cable termination member such that the exposed strength members and optical fibers extend outwardly beyond the end of the cable termination member. The strength members are then fanned out and folded back over a first crimp ring positioned around the termination member, and a second crimp ring is then positioned over the foldedback strength members such that the strength members are positioned between the first and second crimp rings. The second crimp ring is then crimped to the first crimp ring to securely anchor the strength members therebetween.
Securing of the strength members of the optical fiber cable to the cable termination portion of the connector in this way assists in isolating, and thus protecting, the optical fibers within the cable from external stresses applied to the cable jacket, for example, during connection and disconnection of mated connectors.
With the above construction, however, the flexible jacket of the optical fiber cable is often not itself very firmly secured to the connector, and an excessive force can loosen or pull it away from the strain relief thus further exposing the strength members and optical fibers in the cable and rendering the optical fibers more susceptible to being damaged.